• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.371-372
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• 2008

본 논문은 새롭게 초음파 분산기법을 이용하여 제조된 나노콤포지트 와 원형에폭시 수지에 대한 전기적 특성인 트리현상의 여러특성을 연구하였다. 나노필러인 Layered Silicate Particles가 에폭시수지 중에 Power Ultrasonic으로 분산된 나노콤포지트를 제조하였다. 충진된 혼합물에서 나노입자의 영향을 조사하기위해 열적, 구조적 특성을 연구하였고, 장시간 절연파괴 특성을 조사하기위해 침대평판 전극으로 원형에폭시수지와 나노콤포지트와 비교 측정하였다. 연구는 에폭시원형수지에 대한 인가전압레벌(교류 10, 15, 20kV)의 변화와 온도변화에 대한 (30,90,$130^{\circ}C$)의 트리특성을 연구하였다. 모든 전압레벨에서는 일정전압까지 1kV/s 로 승압 후 일정하게 인가되었고, 파괴에 이를 때까지 측정한 결과 10kV, 15Kv, 20KV의 경우 1042,75,488분후에 파괴에 이르렀다. 그러나 트리진행속도는 인가전압이 높을수록 빠르게 진행하였다. 온도 변화에 대한 트리특성으로서 15kV인가 후 파괴에 이르는 시간은 30,90,$130^{\circ}C$의 경우 75.3, 970, 226분으로 $90^{\circ}C$의 경우 절연성능이 가장 우수하였고, 트리진전속도는 $30^{\circ}C,130^{\circ}C,90^{\circ}C$ 순으로 나타났다. 이는 트리진전으로 파괴에 이르는 시간과 속도는 트리형태에 지배적으로 영향을 맡고 있음을 알 수 있었다. 또한 나노콤포지트 트리의 경우 15kV인가시 10902에 파괴에 이르렀고, 트리진전속도는 0.000729mm/min으로 원형에 비하여 53.36배의 트리진전시간이 느리고, 파괴시간은 145배 오래 견디는 절연내력을 측정할 수 있었다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.469-474
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• 2015

In ultrasonic spray pyrolysis deposition, a precursor solution is evaporated by an ultrasonic atomizer, then gas-carried into a furnace where the solute is separated from the water vapor. After condensation, polymerization, and nucleation, the solute oxide forms a thin film. To improve the deposition efficiency, the ultrasonic atomizer was studied to optimize the evaporated gas flow. The vat cover was redesigned, using three versions with different inlet factors being tested through a computational fluid dynamic analysis as well as a water evaporation experiment. The atomization rate with a hemispherical cover with a $30^{\circ}$ inlet was found to be 2.4 times higher than that with the original. This improvement was verified with fluorine-doped tin oxide spray pyrolysis deposition. The film obtained with the modified vat cover was 2.4 times thicker than that obtained with the original vat cover.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.348-351
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• 2012

A vaginal speculum examination of a 17-month-old Holstein heifer with a history of repeated artificial insemination (AI) failures via the cranial vagina revealed the presence of an intact hymen (imperforate hymen) beyond the external urethral orifice, which resembled the vaginal wall. An ultrasonographic examination detected hypoechoic fluid within the vaginal cavity between the intact hymen and the cervix, indicating the presence of hydrocolpos. After sedation and epidural anesthesia, the intact hymen was incised using a scalpel and scissors and removed, while the incised portions were sutured using a simple interrupted method. The heifer became pregnant after three consecutive estruses with the intervals of approximately 20 days and concomitant AIs. The heifer gave birth to a healthy male calf with no complications after a 291-day gestation period. This case reports the presence of an imperforate hymen with hydrocolpos in a Holstein heifer, followed by successful insemination, conception and delivery after removal of the imperforate hymen.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.513-523
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• 2009

The measuring point of the Hangang Bridge affected by tide has some special topographic characteristics due to Nodle Island. Furthermore the submerged weirs located on the upstream and downstream. Therefore flow is separated and joined by Nodle Island. Discharge measurement at the point of the Hangang Bridge is very important, because Hangang Bridge is key station in managing the discharge and flood forecasting. In the past, it was too difficult to measure discharge in tidal conditions. HRFCO(Han River Flood Control Office) installed automatic discharge measurement facilities for solving this problem. Measuring equipments operates and measures discharge every 10 minutes at 2 points(southern and northern section close to Nodle Island), and calculates flow discharge using Chiu's velocity law(Chiu, 1988). In order to verify the results of automatic discharge measurements, manual discharge measurements were carried out by ADCP. In addition, the monthly discharge were also compared.

• KSBB Journal
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• v.18 no.5
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• pp.352-355
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• 2003

${\beta}$-(1,6)-Branched ${\beta}$-(1,3)-D-glucans are known to enhance the immune system in human body, and in most cases have higher molecular weights over 1 MDa. In order to enhance the efficacy of glucans by decreasing their molecular weights, sonication, acid treatment, and enzymatic hydrolysis were tested and compared in this work. Treatment of sonication was effective to decrease the molecular weight to the extent of several dozens of kilo-daltons, but have a risk to disorder the triple helical structure of the glucans. Acid treatment was also an effective method to degrade polysaccharides, but ${\beta}$-(1,6)-branched of the glucan molecules was found to be also hydrolyzed. Treatment of ${\beta}$-(1,3)-glucanase was an effective method to decrease the molecular weight in mild conditions, but could not hydrolyse the highly ${\beta}$-(1,6)-branched ${\beta}$-(1,3)-glucans efficiently.

• Journal of Powder Materials
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• v.17 no.4
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• pp.263-269
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• 2010

Hexagonal barium ferrite ($BaFe_{12}O_{19}$) nano-particles have been successfully fabricated by spraypylorysis process. $BaFe_{12}O_{19}$ precursor solutions were synthesized by self-assembly method. Diethyleneamine (DEA) surfactant was used to fabricate the micelle structure of Ba-DEA complex under various DEA concentrations. $BaFe_{12}O_{19}$ powders were synthesized with addition of Fe ions to Ba-DEA complex and then fabricated $BaFe_{12}O_{19}$ powders by spray-pyrolysis process at the temperature range of $800{\sim}1000^{\circ}C$. The molar ratio of Ba/DEA and heat-treatment temperatures significantly affected the magnetic properties and morphology of $BaFe_{12}O_{19}$ powders. $BaFe_{12}O_{19}$ powders synthesized with Ba/DEA molar ratio of 1 and heat-treated at $900^{\circ}C$ showed the coercive forces (iHc) of 4.2 kOe with average crystal size of about 100 nm.

• Journal of Veterinary Clinics
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• v.32 no.3
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• pp.263-267
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• 2015

Three dogs having adrenal masses detected on ultrasonographic examination were underwent computed tomography (CT) for surgery. After adrenalectomy, each mass was diagnosed pheochromocytoma with myelolipoma, adrenocortical carcinoma and adrenal adenoma through histopathology. Five minutes were used to get delayed enhanced CT images. Attenuation value was measured in each mass and the absolute and relative percentage of enhancement washout were calculated.

• Journal of Veterinary Clinics
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• v.30 no.4
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• pp.305-309
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• 2013

Pyometra is a diestrual, chronic disease process with acute manifestations in the adult, ovary-intact bitch. Serosal inclusion cysts develop during postpartum involution as mesothelium becomes trapped during rapid uterine contraction. A 10-year-old golden retriever bitch presented with lethargy, anorexia, tachypnea, abdominal distention, and abnormal vaginal discharge. Radiographic, ultrasound, and laboratory examinations were performed. On ultrasound examination, the uterus was distended by fluid containing echogenic "snow storm" particles; cystic structures containing anechoic fluid were found adjacent to the body of the uterus. Leukocytosis, neutrophilia, and anemia were diagnosed by a complete blood cell count. The initial diagnosis was pyometra, and an ovariohysterectomy was performed. Macroscopically, the uterine body and horns were expanded and partially adhered to the abdominal wall; numerous cysts containing clear fluid protruded over the entire surface of the uterus. Escherichia coli that was sensitive to enrofloxacin, was cultured from the lumen of the uterus. Histopathological assessment confirmed a final diagnosis of pyometra and serosal inclusion cysts of the uterus.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.157-161
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• 2003

Nowadays there are increasing demands for more accurate measurement of atmospheric pressure according to the development of environmental industries. One of the most important pressure gauges for satisfying these demands is a quartz resonance barometer. In order to calibrate such an accurate barometer, laser/ultrasonic mercury manometers have been used. However, complexity and cost of mercury manometers made it out of use gradually. As a substitute, a gas-operated pressure balance is used for calibration of precise barometers. In such a case, commercially available pressure balances cannot be entirely suitable because consequent exposure of the piston, cylinder and masses to the atmosphere causes the problem of contamination. In this paper a device for changing the masses in situ without breaking the vacuum is described. This device made it possible to add or remove weights in the absolute mode, thereby greatly reducing the time between observations. At the same time, we investigated the characteristics of a commercial precise barometer using this new apparatus.

• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.151-156
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• 2003

Two capacitance diaphragm gauges(CDG) and two resonance silicon gauges(RSG) were calibrated using an ultrasonic interferometer as a national low vacuum standard in KRISS. The CDG has superior pressure resolution and is rugged as well as resistant to over-pressure because of all-metal inner components. Meanwhile, the RSG is a new type of MEMS sensor that has excellent calibration stability and is resistant to mechanical shocks. The calibration uncertainties were analyzed according to the ISO procedures. Results showed that the maximum difference of the expanded uncertainties was $9\times10^{-3}$Pa at the generated pressure of 100 Pa for the two different types. It is remarkable that the RSG can be used as a transfer standard at low vacuum since their accuracies were found to be within 0.5 %.